Hypervelocity propulsion arrangement



March 31, 1964 x, MEYER 3,126,789

HYPERVELOCITY PROPULSION ARRANGEMENT Filed May 17, 1962 FIG.4.

L- fl Ef- RUDOLF x. MEYER 2 VACUUM PUMP INVEN TOR.

ATTORNEY.

United States Patent Ofilicc 3,126,789 Patented Mar. 31, 1964HYPERVELOCITY PROPULSION ARRANGEMENT Rudolf X. Meyer, Pacific Palisades,Calih, assignor to The Aerospace Corporation, Los Angeles, Calif., acorporation of California Filed May 17, 1962, Ser. No. 195,513 14Claims. (Cl. 898) The present invention relates to the high-strengthmagnetic field art and more particularly relates to means for propellingprojectiles at hypervelocities by means of magnetic fields.

Hypervelocity projection arrangements or guns are useful in severalkinds of re-entry laboratory activities wherein a projectile is driveninto a low pressure tank for simulating orbital velocity re-entryproblems. Although certain hypervelocity guns are known in the priorart, the maximum velocity attainable is of the order of 30,000 ft. persecond. However, velocities substantially above this will provideinformation concerning deep-space probe reentry problems as well asorbital re-entry problems. Moreover, the attaining of velocitiessubstantially above 30,000 ft. per second will provide means for testingmeteorite damage in a manner similar to tests already accomplishedconcerning micro-meteorite phenomena. Furthermore, projectile velocitiessubstantially in excess of expected space vehicle velocity may provide afeasible space weapon.

One example of a prior art hypervelocity gun is a lightgas gun utilizingthe compression of a light gas to drive the projectile by the driving ofa relatively large cylindrical piston through an enclosed breech chambercontaining the light gas toward the projectile at the far end thereof.The projectile is substantially smaller in diameter than the piston andthe chamber. When the piston is driven by a high-explosive to compressthe light-gas, pressures of 40,000 p.s.i. are typical. However, theperformance is fundamentally limited by the finite velocity of sound inthe gas within the enclosed chamber. At any given time, the gas pressurenear the projectile is only a fraction of the pressure near the piston,resulting in lower acceleration to limit terminal velocity of theprojectile. Equilibration of pressure in the chamber proceedsessentially at sound velocity. Thus, energy transmission from the pistonto the projectile is a function of the velocity of sound of the lightgas.

Usually, with this arrangement the time during which the projectile isaccelerated is not long enough to let the pressure equilibrate. As aconsequence of incomplete equilibration a differential acceleration of aprojectile occurs, with a maximum force being applied to the projectileduring its initial acceleration phase and with the applied forcedecreasing to a lesser amount as the projectile accelerates. Since manyprojectiles will include simple electronic detecting arrangements, theymay be constructed to withstand maximum accelerations creating nogreater than 20,000 to 50,000 G loadings. However, even when noelectronic circuit is provided in the projectiles, there is always afinite limit of the maximum feasible acceleration loading of aprojectile because of the problem of the plastic deformation of theprojectile itself. One approach has been to provide arrangements whichdevelop a more uniform accelerating force throughout the accelerationperiod of the projectile.

In order to accomplish this, it has even been proposed to preheat thelight gas as by the use of an arch discharge, to increase itstemperature and thus increase the velocity of sound therein. 20,000 to60,000 p.s.i. are typical and projectile velocities as high as 20,000 to30,000 feet per second may be at tained. However, the limitations due tothe finite sound In such arrangements, pressures of velocity cannot becompletely overcome whereby velocities greater than about 30,000 feetper second appear to be unattainable by use of a light-gas gunarrangement.

It is, therefore, an object of my invention to provide a new andimproved hypervelocity gun arrangement which is not subject to thelimitations of sonic velocities by using a magnetic force as the drivingforce between a driving piston and a projectile.

A further object of my invention is to provide a new and improvedhypervelocity projection arrangement.

According to one embodiment of the present invention a magnetic field iscreated between two parallel conductors lying on opposite sides of abreech chamber by the discharging of a high voltage capacitor throughthese conductors with a connection therebetween being the projectile ofthe arrangement. At the instant the current flow reaches its maximumvalue, a conductive piston is driven at high velocity toward theprojectile while engaging both of the conductors and thereby shuntingthem and maintaining the maximum current flow in the loop circuit thuscreated. The establishing of this short circuited current loop traps themagnetic flux therein. The velocity of the driven piston tends to reducethe area of the short circuited loop circuit at a rate creating anextremely rapid magnetic field buildup. This magnetic field buildup isre lieved by acceleration of the projectile and the velocity limit oflight-gas guns is essentially removed by substituting the propagationvelocity of electromagnetic waves in a wave guide (approximately thespeed of light) for the velocity of sound. This arrangement alsofacilitates charges of gas for shock tube purposes.

The subject matter which is regarded as this invention is particularlypointed out and distinctly claimed in the concluding portion of thespecification. The invention, however, as to its organization andoperation, together with further objects and advantages thereof, willbest be understood by reference to the following description taken inconnection with the accompanying drawing in which:

FIG. 1 is a cross sectional plan view of one embodiment of the presentinvention;

FIG. 2 is a cross sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a cross sectional view taken along the line 3-3 of FIG. 1;

FIG. 4 is a view similar to FIG. 1 showing another embodiment of myinvention; and

FIG. 5 is a partial side elevational view showing still anotherembodiment of my invention.

Referring now to the drawing, wherein like numerals refer to similarparts, in FIG. 1, a projectile 10 is positioned within a bore 12 of agun barrel 13 near the end thereof adjacent to an enlarged breech 14. Atthe opposite end of the breech 14 is a piston 15 which willsubstantially fill a breech chamber 16. The piston 15 is arranged to belong enough to prevent tumbling or skewing. The upper portion of thebarrel 13 includes a condoctor 17 fabricated from a low resistance metalsuch as copper or silver alloys. The conductor 17 extends through theenlarged breech region of the gun as indicated by the numeral 17'.Similarly, the lower portion of the barrel 13 is fabricated to include alow resistance conductor 18 which extends throughout the length of thebreech 14 as indicated by the numeral 18'. These conductors definerespectively diametrically opposed arcuate surfaces of the bore 12. Incertain arrangements requiring bore rifling, the conductors 17 and 18are spiraled. spiraling also is used to assure good electrical contactbetween the couductors and the projectile 10.

As illustrated more clearly in FIGS. 2 and 3, the conductors 17 and 18occupy a relatively small portion of thebarrel circumference in thepresent invention and are not coupled electrically except through theprojectile 10.

To prevent undesired electrical coupling, a substantial portion of thebarrel 13 is constructed of an insulating material 20 such as epoxyresin or Mylar. The gun itself is completed by a casing 22 whichcontains the magnetic force, protects the dielectric insulating material20 and provides a construction which is readily secured to carryingvehicles or other portions of the equipment. It should also be notedthat for the magnitude of flux contemplated, all adjacent metal partsare saturated whereby the path of the flux 23 is not limited to thestructural elements.

FIG. 2 also indicates an electrical connection between conductors l7 andit; only through the projectile 10. Because of the requirement of a lowresistance system, the projectile 10 should be slightly larger than thebore 12 to provide a good connection between the conductors 1'7 and 18and to provide a means for initially preventing undesired movement ofthe projectile 10. With the current flows of the present invention, atleast the rear surface of the projectile 10 should be made of a highlyconductive material which has sufiicient physical and thermal strengthto withstand the operations contemplated. Certain metals such as nickel,copper, silver, and gold alloys will provide these basiccharacteristics. Usually it is preferably to provide a conductivesliding lubrication arrangement between the conductive portions of thepresent invention such as those used in commutating brushes or trolleycollectors. This includes certain carbon and metallic graphite surfacematerials and various other lubricants. On the other hand, ablating orother materials for testing purposes may be used in the fabrication ofthe forward conical end of the projectile 10.

Similarly, at least the leading surface of the piston 15 should be of alow resistance material to obtain maximum utilization of the shuntedmagnetic field of the present invention. Since the entire operation ofthe present invention is accomplished in a millisecond or so, a majorportion of the current flow is on the surface of the conductive portionsof the loop circuit whereby relative efficient and expensive conductingsurface coatings may be utilized without requiring a great mass ofprecious metals.

It should be noted from FIGS. 1 and 3 that although the piston 15 isplaced behind the upper and lower conductor extensions 17 and 18' it isof a diameter sufficient to engage electrically both of these conductorsduring its travel through the breech chamber 16. Moreover, it ispreferred that the piston 15 have substantially more mass than theprojectile 10 so that the magnetic force of the present invention ismore effective in accelerating the projectile 10 than it is indecelerating the piston 15.

The electrical circuit of the present invention is illustratedschematically in PEG. 1 as a large capacitor 24 which is charged from apower supply 25, a sequentiallyoperable switch 26, leads coupling theswitch 26 and the opposite side of the capacitor 24 to the conductorextensions 17 and 18 at a point adjacent to the piston 15 and a triggermechanism 28. The remaining portions of the gun include a primarypropellant means such as a charge of high explosive 30 placed directlybehind the piston 15 and, in the particular construction illustrated inFIG. 1, Within a cartridge 32 which is secured to the casing 22 by anyconventional means such as a threaded engagement. etonation of thecharge 30 may be accomplished by any convenient means such as a morevolatile cap charge 34 which is ignited by a spark plug arrangement 36.Both the switch 26 and the spark plug arrangement 36 are sequentiallycontrolled by the trig ger 28.

Depending on the particular dimensions and materials utilized and thevoltage which may be applied to the capacitor 24, the curernt in theloop circuit including the conductor 17'17, the projectile 10, and theconductor lit-18 will build up a maximum value of many thousands ofamperes in a millisecond or less, after the closing of the switch 26.Moreover, the detonation of the charge 30 in response to a spark fromthe spark plug arrangement 36 will result in the piston 15 engaging theconductor extensions 17'18' within a similar short period. The exactreaction time of the piston 15 to the spark depends on the particularpropellant material used in the charge 30 and the configuration of thecartridge 52. Thus, once the capacitor 24 has been charged to itsmaximum voltage, such as 50 kilovolts, the switch 26 and a spark plugarrangement 36 may be operated simultaneously or with a time sequence ofa few hundred microseconds to obtain initial short-circuiting of theloop circuit including the piston 15, the projectile l0, and theconductor It18' at the precise instant maximum current flow is attained.

With respect to the projectile 10 itself the basic driving force isessentially the same as that used in an induction motor. The loopcircuit current generates a high magnetic flux within the loop, and thecurrent flow in the projectile 10 is repulsed. The flux density is afunction of the area of the loop as well as the current flow around theloop circuit. As the piston 15 is forced toward the projectile 10, theflux density is increased rapidly by the rapid reduction of the areathrough which the flux must pass. In the time durations involved thetotal flux is not reduced substantially. As a result, the magnetic forceincreases inversely proportional to the square of the loop circuit areareduction. As the projectile 10 moves forward, after overcoming theinitial movement restriction, the magnetic pressure is relieved.

Because of the disparity in the diameters of the piston 15 (and thechamber 16) and the projectile 10 (and the bore 12), the projectile 10must move a far greater distance to compensate for movement of thepiston 15 (in an attempt) to maintain constant magnetic forces. Forinstance, with a disparity in diameters of 5 to 1, magnetic equilibriumcould be maintained if the projectile 10 moved 5 times as far per unittime as the piston 15. At least during the initial travel of the piston15, such relative movement is not attainable. This phenomenon is assuredby the providing of means such as a press fit for restricting theinitial movement of the projectile 10. Thus, the projectile does notmove until after the magnetic force starts to increase because ofmovement of the piston 15. The Maxwellian magnetic force created toaccelerate the projectile 10 may be arranged to develop forces whichfacilitate hypervelocity projection at velocities substantially abovethe 30,000 feet per second attainable with light-gas guns. In mostapplications of the present invention the overall length of my gun willbe of the order of fifty feet to attain velocities in excess of 50,000feet per second.

It is relatively obvious that if the breech 14 and the bore 12 are madevery long, the magnetic force may be effectively used to attain maximumvelocity of the projectile. This maximum velocity is a function, amongother things, of the maximum velocity attainable by the piston 15. Thus,driving the piston 15 at a low velocity will create neither as great amagnetic force, nor as great a velocity of the projectile 10, as ahigh-velocity piston.

Therefore, referring now to FIG. 4, I have shown an arrangementproviding an extremely high velocity piston 15'. The piston 15' issubstantially the same as the piston 15 with respect to the conductor1717, a projectile 10 and the conductor 1818. However, the means ofpropelling the piston 15' has been substantially changed compared tothat shown in FIG. 1, by the replacing of the cartridge 32 and the highexplosive charge 30 with a light-gas gun 40 which includes an enlargedbreech chamber 41 fillable with a light gas from a source 42 bysequential operation of the valves 43 and 43'. At the rear of theenlarged breech chamber 41 is an enlarged piston 44 which, because I amnow utilizing a light-gas gun, may include a resilient seal ring 45. Ahigh explosive charge 30' is secured behind the enlarged piston 44 by abreech plug 46.

In order that the light gas from the source 42 maybe contained in theenlarged breech chamber 41, the piston 15' is provided with a sealingmeans 48 on a rear portion which is flanged outward and arranged toengage tightly the tapered end surface 49 of the enlarged breech chamber41. The sealing arrangement shown operates in the same manner asordinary valve seats in conventional internal combustion engines. Inthis manner the lightgas pressure in the enlarged breech chamber 41 canbe raised substantially above atmospheric pressure prior to thetriggering of the gun. The tight fit of the projectile 10 also allowsthe obtaining of a substantial magnetic force prior to the initialmotion of the projectile.

I have considered additional innovations to accomplish increasedvelocity of the projectile 10 that include substantial evacuation of thebreech chamber 16' and the bore 12' to prevent the mass of any gasestherein from substantially reducing the velocities attainable, by thephenomenon of effectively increasing the mass of both the piston 15 andthe projectile 10'. In order to accomplish substantial vacuum in theseportions, a rupturable diaphragm seal 50 is provided at the end of thebarrel 13 as illustrated in FIG. 4. The seal 50 is mounted in a mannerallowing substantial reduction of the pressure within these portions ofthe gun. Even with the vacuum contemplated suflicient pressure will bebuilt up by the motion of the projectile 10' to rupture the seal d.Moreover, the seal 50 is arranged to be ruptured in a way removing itfrom the flight path of the projectile prior to any physical contacttherebetween whereby the projectile 10' will not be deflected in any waybecause of the use of the seal 50.

The operation of my invention, as illustrated in FIG. 4, combines thefeatures of a light-gas gun and the embodiment of my invention shown inFIG. 1. A triggering arrangement 28' is similar to that shown in FIG. 1as 28, but because of its having more functions to perform, is slightlymore complex. A first series of operations controlled by the trigger28', includes evacuating the bore 12', and the breech chamber 16' byenergizing a vacuum pump arrangement 52. The pressure diiferentialdeveloped across the piston assures a tight seal in the region of thesealing means 48. As soon as this tight seal has been accomplished withthe valve 43' open, a light gas is admitted to the enlarged breechchamber 41 by opening the valve 43. The ports 54 and 56 in the enlargedbreech chamber 41 are arranged to provide relatively complete scavengingof the air, much in the same manner as scavenging is accomplished in a2-cycle combustion engine. As soon as the enlarged breech chamber 41 issubstantially filled with light gas, the valve 43 is closed, and thepressure within the enlarged breech cham ber 41 is raised aboveatmospheric pressure.

Because of the increased number of operations necessary to initiatemotion of the piston 15', it may be expected that the time delay betweeninitiation of a spark arrangement 36 and the engagement of the conductorextensions 17 and 18' will be longer than that necessary to attainmaximum current flow in the loop circuit components 17'-17, 10' and1818. Therefore, in most operations contemplated, the trigger 28'energizes the spark arrangement 36' an instant before closing the switch26.

The explosion of the charge 30' moves the piston 44 toward the piston15' and substantially increases the pressure until the sealing means 48is ruptured, whereupon the piston 15' is driven rapidly to shunt theloop circuit. The remaining operation of the arrangement issubstantially identical to that described above in connection with FIG.1.

As will be apparent to those familiar with the art of the'presentinvention,there are many uses for the present invention. For instance,either of the projectiles 10 or 10 is usable as a cylindrical piston 10"to drive a pre selected charge of air from a high pressure cartridge 58into a shock tunnel arrangement at velocities greater than orbitalvelocities. In such arrangements the charge of air maybe provided by themass or charge of air normally residing in the bore 12', or, when a moreprecisely controlable system is necessary, by air or other gas containedwithin the cartridge 58 between two spaced apart rupturable diaphragmsas that illustrated at 50' and 50 in FIG. 5. Moreover, although the bore13" of the cartridge 58 is substantially the same diameter as the bore12 or the bore 12, I have provided a smaller exhaust port 59 so that thecylindrical projectile 10" is prevented from escaping into the shocktunnel test area. A similar small exhaust port 39 may be secured to thebarrel 13 of FIG. 1 when it is desired simply to project the air withinthe bore 12 into a test area. Rupturable diaphragm 50 may also be usedto define the mass of air projected.

While I have shown and described particular embodiments of the presentinvention, further modifications may occur to those skilled in this art.For instance, when the entire gun is in an evacuated environment, thebreech 14 and the barrel 13 may be provided with apertures or otherwisehave lateral openings therein, so long as sufficient support is providedto prevent tumbling or other loss of contact between the piston, theconductors and the projectile which form the high current loop circuit.I desire it understood, therefore, that my invention is not limited tothe particular form shown and I intend by the appended claims to coverall such modifications which do not depart from the true spirit andscope of my invention.

I claim:

1. A hypervelocity gun arrangement comprising:

a gun barrel defining a bore;

a first conductor within said barrel defining a first arcuate surface ofthe bore throughout the length thereof;

a second conductor defining a second arcuate surface of the borediametrically opposed to said first arcuate surface;

an enlarged breech secured to said barrel at one end thereof anddefining an enlarged breech chamber;

said first and second conductors each having extensions extending alongdiametrically opposed arcuate surfaces of the breech chamber;

a projectile positionable in the bore adjacent to said breech and of adiameter sufficient to electrically engage both of said conductorsthroughout the length of the bore;

a piston positionable adjacent to the end of said extensions in thebreech chamber and of a diameter sufficient to engage both of saidextensions throughout the length of the breech chamber;

means for inducing electric current flow of the order of thousands ofamperes through said extensions and said projectile to create a magneticforce for accelerating said projectile through the bore;

and means for driving said piston through the breech chamber toward saidprojectile so that it will engage said extensions at an instant when thecurrent flow is maximum, whereby said piston initially shortcircuits thecurrent flow in the loop circuit established thereby and sequentiallyincreases the magnetic flux thereof to increase rapidly the magneticforce on said projectile, the relative diameter of the breech chamberand the bore being such that said :proj'ectile must move a greaterdistance than said piston to maintain 'the area of said loop circuitconstant.

2. A'hypervelocity gun arrangement comprising:

a gun barrel defining a bore;

a first'conductor Within said barrel defining a first arcuate surface ofthe bore throughout the length thereof;

a second conductor defining a second arcuate surface of the boreopposite to said first arcuate surface;

an enlarged breech secured to said barrel at one end thereof anddefining an enlarged breech chamber, said first and second conductorshaving extensions extending along diametrically opposed arcuate surfacesof the breech chamber;

a projectile positionable in the bore adjacent to said breech and of adiameter sufficient to electrically engage both of said conductorsthroughout the length of the bore;

a piston positionable adjacent to the end of said extensions in thebreech chamber and of a diameter suflicient to couple electrically bothof said extensions throughout the length of the breech chamber;

means for inducing electric current flow of the order of thousands ofamperes through said extensions and said projectile to create a magneticforce for accelcrating said projectile through the bore;

means for preventing the initial movement of said projectile until saidmagnetic force exceeds a predetermined magnitude; and

means for driving said piston through the breech chamber toward saidprojectile so that it will engage said extensions at an instant when thecurrent flow is maximum, whereby said piston initially shortcircuits thecurrent flow in the loop circuit established thereby and sequentiallyincreases the magnetic flux thereof to increase rapidly the magneticforce on said projectile, above said predetermined minimum.

3. A hypervelocity gun arrangement comprising:

a gun barrel defining a bore;

a pair of conductors within said barrel defining opposed arcuatesurfaces of the bore throughout the length thereof;

an enlarged breech secured to one end of said barrel and defining anenlarged breech chamber;

a pair of extensions of said pair of conductors respec tively andpositioned along opposed arcuate surfaces of breech chamber;

a projectile positionable in the bore adjacent to said breech andarranged to couple electrically said pair of conductors throughout thelength of the bore;

a piston positionable adjacent to the end of said pair of extensions andarranged to couple said pair of extensions throughout the length of thebreech chamber only after initial movement thereof;

first restricting means for preventing the initial movement of saidpiston;

means for inducing electric current flow of the order of thousands ofamperes through said pair of extensions and said projectile to create amagnetic force for accelerating said projectile through the bore;

second restricting means for preventing the initial movement of saidprojectile until said magnetic force exceeds a predetermined magnitude;and

means for developing suflicient force to overcome said first restrictingmeans for driving said piston through the breech chamber toward saidprojectile so that it will couple said pair of extensions at an instantwhen the current flow is maximum, whereby said piston initiallyshortcircuits the current flow in the loop circuit established therebyand sequentially increases the magnetic flux thereof to increase rapidlythe magnetic force on said projectile to overcome said secondrestricting means.

4. A hypervelocity gun arrangement comprising:

a gun barrel defining a bore;

a pair of conductors within said barrel defining opposed arcuatesurfaces of the bore throughout the length thereof;

a pair of parallel extensions of said pair of conductors respectivelywhich are spaced apart several times the diameter of the bore;

a projectile positionable in the bore adjacent to said extensions andarranged to couple electrically said pair of conductors throughout thelength of the bore;

a piston positionable adjacent to the end of said pair of extensions andarranged to couple said pair of xtensions throughout the length thereofonly after initial movement of said piston;

restricting means for preventing the initial movement of said piston;

means for inducing electric current flow of the order of thousands ofamperes through said pair of extensions and said projectile to create amagnetic force for accelerating said projectile through the bore;

a high explosive driving means for developing sufficient force toovercome said restricting means to drive said piston toward saidprojectile so that it will couple said pair of extensions at an instantwhen the current how is maximum, whereby said piston initiallyshortcircuits the current fioW in the loop circuit established therebyand sequentially increases the magnetis flux thereof to increase rapidlythe magnetic force on said projectile whereby said projectileaccelerates through the bore to relieve the magnetic force.

5. A hypervelocity gun arrangement comprising:

a gun barrel defining a bore;

a pair of conductors within said barrel defining opposed arcuatesurfaces of the bore throughout the length thereof;

a breech secured to said barrel at one end thereof, said pair ofconductors each having an extension defining diametrically opposedarcuate inner surfaces of said breech;

a projectile positionable in the bore adjacent to said breech and of adiameter sufficient to electrically couple said pair of conductorsthroughout the length of the bore;

a piston positionable adjacent to the end of said extensions in thebreech chamber and of a diameter sufficient to couple electrically saidpair of extensions throughout the length of said breech;

means for inducing electric current flow of the order of thousands ofamperes through said extensions and said projectile to create a magneticforce for accelerating said projectile through the bore; and

light-gas gun means for driving said piston rapidly through said breechtoward said projectile so that said piston engages said extensionsduring an instant when the current flow is maximum, whereby said pistoninitially shortcircuits the current flow in the loop circuit establishedthereby and sequentially increases the magnetic flux thereof to increaserapidly the magnetic force on said projectile.

6. A hypervelocity gun arrangement comprising:

a pair of parallel conductors defining opposed arcuate surfaces;

means for maintaining said pair in a predetermined spaced relationship;

said pair of conductors each having an extension defining diametricallyopposed arcuate surfaces having substantially greater spacing,therebetween than said pair of conductors;

a projectile positionable between said pair of conductors adjacent tosaid conductor extensions and of a diameter sufiicient to electricallycouple said pair of conductors throughout the length thereof;

a piston positionable adjacent to the end of said conductor extensionsremote from said projectile and of a diameter sufiicient to coupleelectrically said conductor extensions throughout the length thereof;

means for inducing electric current flow of the order of thousands ofamperes through said conductor extensions and said projectile to createa magnetic force for accelerating said projectile along said conductors;and

light-gas gun means for driving said piston rapidly along said conductorextensions toward said projectile so that said piston engagessaid-extensions during an instant when the current flow is maximum,whereby said piston initially short-circuits the current flow in theloop circuit established thereby and sequentially increases the magneticflux thereof toincrease rapidly the magnetic force on said iprojectile.

7. A hypervelocity gun arrangement comprising:

a pair of parallel conductors defining opposed arcuate surfaces;

said pair of conductors each having an extension defining diametricallyopposed arcuate surfaces having substantially, greater spacingtherebetween than said pair of conductors;

a projectile positionable between said pair of conductors adjacent tosaid conductor-extensions and of a diameter sufficient to electricallycouple said pair of conductors throughout the length thereof;

a piston positionable adjacent to the end of said conductor extensionsremote from said projectile and of a diameter suflicient to coupleelectrically said conductor extensions throughout the length thereof;

means for inducing electric current flow of the order of thousands ofamperes through said conductor extensions and said'projectile to createa magnetic force for accelerating said projectile along said conductors;and

means for driving said piston-rapidly along said conductor extensionstoward said projectile so that said piston engages said extensions andsequentially increases the magnetic flux of the loop circuit createdthereby to increase rapidly the magnetic force on said projectile.

8. A hypervelocity projection arrangement comprising:

a pair of parallel conductors defining opposed arcuate surfaces;

said' pair of conductorseach having an extension defining diametricallyopposed arcuate surfaces having substantially greater spacingtherebetween than said pair of conductors;

means for evacuating the region between said pair of conductors andbetween said conductor extensions;

a projectile positionable between said pair of conductors adjacent tosaidconductor extensions and of a diameter sutficient to electricallycouple said pair of conductors throughout the length thereof;

a piston positionable adjacent to the end of said conductor extensionsremote from said projectile and of a diametersuficient to coupleelectrically said conductor extensions throughout the length thereof;means for inducing rapidly electric current flow of the order ofthousands of amperes through said conductor extensions and saidprojectile to create a magnetic force for accelerating said projectilealong said conductors;

said pair of conductors, said conductor extensions, the rear of saidprojectile, and the leading portion of said pistoneach being providedwith low resistance surfaces to facilitate rapid changes of current flowthereover;

and light-gas gun means for driving said piston rapidly along saidconductor extensions toward said projectile so that-said pistonengagessaid extensions during an instant when the current flow ismaximum, whereby said piston initially short-circuits the current flowin the loop circuit established thereby and sequentially increases themagnetic flux thereof to increase rapidly the magnetic force on saidprojectile.

9. A hypervelocity projection arrangement comprising:

a pair of parallel conductors defining opposed arcuate surfaces;

said pair of conductors each having an extension defining diametricallyopposed arcuate surfaces having substantially greater spacingtherebetween than said pair of conductors;

means for evacuating the region between said pair of conductors;

'a projectile positionable between said pair of conductors adjacent tosaid conductor extensions and of a diameter sufficient to electricallycouple said pair of conductors throughout the length thereof;

a piston positionable adjacent to the end of said conductor extensionsremote from said projectile and of a diameter sufiicient to coupleelectrically said conductorextensions throughout the length thereof;

means for inducing rapidly electric current flow of the order ofthousands of amperes throughsaid conductor extensions and saidprojectile to create a magnetic force foraccelerating said projectilealong said conductors;

said pair of conductors, said conductor extensions, the rear of saidprojectile, and the leading portion of said piston each being providedwith low resistance surfaces to facilitate rapid changes of current flowthereover;

and means for driving said piston rapidly along said conductorextensions toward said projectile so that said piston engages saidextensions during an instant when the current flow is maximum, wherebysaid piston initially short-circuits the current flow in the loopcircuit established-thereby and sequentially increases the magnetic fiuxthereof to increase rapidly the magnetic force on said projectile.

10. A hypervelocity projection arrangement comprisa pair of parallelconductors defining opposed arcuate surfaces;

' said pair of conductors each having an extension definingdiametrically opposed arcuate surfaces having substantially greaterspacing therebetween than said pair of conductors;

means for evacuating the region between said pair of conductors; aprojectile positionable between said pair of conductors adjacentto saidconductor extensions and of a diameter sufficient to electrically couplesaid pair of conductors throughout the length thereof;

a piston positionable adjacent to the end of said conductor extensionsremote from said projectile and of a diameter sufiicient to coupleelectrically said' conductor extensionsthroughout the length thereof;

means for inducing rapidly electric current flow of the order ofthousands of amperes through said conductor extensions and saidprojectile to create a magnetic force for accelerating said projectilealong said conductors;

and means for driving said piston rapidly along said conductorextensions toward said projectile so that said piston engages saidextensions during an instant when the current flow is maximum, wherebysaid piston initially short-circuits the current flow in the loopcircuit established thereby and sequentially increases the magnetic fluxthereof to increase rapidly the magnetic force on said projectile.

11. A hypervelocity projection arrangement comprisa pair of parallelconductors defining opposed arcuate surfaces;

said pair of conductors each having at one end thereof an extensiomsaidconductor extensions defining di- 65 -ametrically opposed arcuatesurfaces having substantially greater spacing therebetween than saidpair of conductors;

a high pressure cartridge securable to the other end of said pair ofconductors and having a bore there- 70 through;

means for sealing said bore to contain therein a predetermined charge ofgas;

a cylindrical projectile positionable between said pair of conductorsadjacent to said conductor extensions and of a diameter sufiicient toelectrically couple said pair of conductors throughout the lengththereof and to substantially fill said bore of said cartridge;

a piston positionable adjacent to the end of said conductor extensionsremote from said projectile and of a diameter sufiicient to coupleelectrically said conductor extensions throughout the length thereof;

means for inducing electric current flow of the order of thousands ofamperes through said conductor extensions and said projectile to createa magnetic force for accelerating said projectile along said conductors;and

means for driving said piston rapidly along said conductor extensionstoward said projectile so that said piston engages said extensions andsequentially increases the magnetic flux of the loop circuit createdthereby to increase rapidly the magnetic force on said projectile.

12. A hypervelocity projection arrangement comprising:

a barrel defining a bore;

a pair of conductors within said barrel defining opposed arcuatesurfaces of the bore throughout the length thereof;

a pair of parallel extensions of said pair of conductors respectively,which are spaced apart several times the diameter of the bore;

a projectile positionable in the bore adjacent to said extensions andarranged to couple electrically said pair of conductors throughout thelength of the bore during its travel through the bore;

means for entrapping a predetermined mass of fluid in the path of saidprojectile;

said means having an inner diameter substantially equal to the diameterof said projectile;

a piston positionable adjacent to the end of said pair of extensions andarranged to couple said pair of extensions throughout the length thereofonly after initial movement of said piston;

means for inducing electric current flow of the order of thousands ofamperes through said pair of extensions and said projectile to create amagnetic force for accelerating said projectile through the bore todrive before it the mass of entrapped fluid;

driving means for developing suflicient force to drive said pistontoward said projectile so that it will couple said pair of extensions atan instant when the current flow is maximum, whereby said pistoninitially short circuits the current flow in the loop circuitestablished thereby and sequentially increases the magnetic flux thereofto increase rapidly the magnetic force on said projectile whereby saidprojectile accelerates through the bore to relieve the magnetic force.

13. A hypervelocity projection arrangement comprising:

a pair of parallel conductors defining opposed arcuate surfaces;

said pair of conductors each having at one end thereof an extension,said conductor extensions defining diametrically opposed arcuatesurfaces having substantially greater spacing therebetween than saidpair of conductors;

a high pressure cartridge having one end securable to the other end ofsaid pair of conductors and having a bore therethrough and having theother end restricted in size;

means for sealing said bore to contain therein a predetermined charge ofgas;

a cylindrical projectile positionable between said pair of conductorsadjacent to said conductor extensions and of a diameter sufficient toelectrically couple said pair of conductors throughout the lengththereof, to substantially fill said bore of said cartridge and beconfined by the restriction in size of said cartridge;

a piston positionable adjacent to the end of said conductor extensionsremote from said projectile and of a diameter suflicient to coupleelectrically said conductor extensions throughout the length thereof;

means for inducing electric current flow of the order of thousands ofamperes through said conductor extensions and said projectile to createa magnetic force for accelerating said projectile along said conductors;and

means for driving said piston rapidly along said conductor extensionstoward said projectile to increase rapidly the magnetic force on saidprojectile.

14. A hypervelocity projection arrangement comprising: 7

a pair of parallel conductors defining opposed arcuate surfaces;

said pair of conductors each having at one end thereof an extensiondefining diametrically an arcuate surface with said conductor extensionshaving substantially greater spacing therebetween than said pair ofconductors;

means for evacuating the region between said pair of conductors andbetween said conductor extensions;

a high pressure cartridge securable to the other end of said pair ofconductors and having a bore therethrough;

means for sealing said bore to contain therein a predetermined charge ofgas;

a cylindrical projectile positionable between said pair of conductorsadjacent to said conductor extensions and of a diameter sufiicient toelectrically couple said pair of conductors throughout the lengththereof; and to substantially fill said bore of said cartridge;

means for stopping said projectile after it has completed its passagethrough said bore;

a piston positionable adjacent to the end of said conductor extensionsremote from said projectile and of a diameter sufficient to coupleelectrically said conductor extensions throughout the length thereof;

means for inducing rapidly electric current flow of the order ofthousands of amperes through said conductor extensions and saidprojectile to create a magnetic force for accelerating said projectilealong said conductors;

said pair of conductors, said conductor extensions, the rear of saidprojectile, and the leading portion of said piston each being providedwith low resistance surfaces to facilitate rapid changes of current flowthereover;

and light-gas gun means for driving said piston rapidly along saidconductor extensions toward said projectile so that said piston engagessaid extensions during an instant when the current flow is maximum,whereby said piston initially short circuits the current flow in theloop circuit established thereby and sequen tially increases themagnetic flux thereof to increase rapidly the magnetic force on saidprojectile.

No references cited.

1. A HYPERVELOCITY GUN ARRANGEMENT COMPRISING: A GUN BARREL DEFINING ABORE; A FIRST CONDUCTOR WITHIN SAID BARREL DEFINING A FIRST ARCUATESURFACE OF THE BORE THROUGHOUT THE LENGTH THEREOF; A SECOND CONDUCTORDEFINING A SECOND ARCUATE SURFACE OF THE BORE DIAMETRICALLY OPPOSED TOSAID FIRST ARCUATE SURFACE; AN ENLARGED BREECH SECURED TO SAID BARREL ATONE END THEREOF AND DEFINING AN ENLARGED BREECH CHAMBER; SAID FIRST ANDSECOND CONDUCTORS EACH HAVING EXTENSIONS EXTENDING ALONG DIAMETRICALLYOPPOSED ARCUATE SURFACES OF THE BREECH CHAMBER; A PROJECTILEPOSITIONABLE IN THE BORE ADJACENT TO SAID BREECH AND OF A DIAMETERSUFFICIENT TO ELECTRICALLY ENGAGE BOTH OF SAID CONDUCTORS THROUGHOUT THELENGTH OF THE BORE;